Africa |
Above: Akosombo hydroelectric power station on the Volta River supplies energy to almost all of Ghana and half of Togo in West Africa
j that longer and more severe droughts could become the norm not only in Africa but also in other parts of the world. Over the past 20 years, droughts have already increased by 29%. Over one in four people live in countries affected by water stress, and by 2050 more than five billion people might suffer from water scarcity, threatening 45% of the world’s economy. Possibly most notable among the water security crises of 2021, Simalabwi says, is what has been called the first “climate change induced famine” where the food crisis in Madagascar left 1.3million people in need of humanitarian aid. Last year drought also ravaged the Horn of Africa, an historically semi-arid region where 70% of the population live in areas that are prone to food shortages and resulted in deterioration of crop fields and loss of livestock in Kenya, Somalia, and Ethiopia. Abnormal dryness also characterised the Angolan 2020/2021 rainy season and pushed people to migrate out of the country in search of water, food, medical services, and economic opportunity. Water sits at the centre of the climate change devastation of Africa, Simalabwi says, because it is felt through the impact on already vulnerable water resources. In addition, according to the IPCC, the region’s rate of surface temperature increase has generally been faster than the global average, and the frequency and intensity of heavy precipitation events are projected to increase in almost all sub-regions. Water crises can only be eased if water is treated as
a top priority by international climate policy makers and if countries manage their water resources in an integrated way. GWP says that there is still a lack of
political will to commit enough resources that will result in better, more efficient, and more sustainable water resources management, and calls for investment in African water security to be made a priority in 2022. However, the Glasgow Climate Pact, signed at the 2021 United Nations Climate Change Conference, does offer some hope that the situation could improve for Africa: a region which contributes only 4% of global emissions yet has the greatest risk to climate hazards. The Pact commits developed nations to at least double their collective provision of climate finance for adaptation to developing countries from 2019 levels (US$80billion) by 2025. “Africa needs a coordinated and collaborative
approach to ensure that developed nations honour their financial commitments and that climate funding reaches vulnerable societies,” Simalabwi says, “specifically addressing water security, which binds so much of collective social, economic, and ecological objectives.”
Looming crisis The World Meteorological Organisation (WMO)
says that global water resource management is “fragmented and inadequate” and highlights the need for urgent action to improve cooperative water management, embrace integrated water and climate policies and scale up investment. WMO Secretary-General Professor Petteri Taalas said: “Lack of water continues to be a major cause of concern for many nations, especially in Africa. More than two billion people live in water-stressed countries and suffer lack of access to safe drinking water and sanitation.”
Booming Mozambique The largest hydroelectric scheme in southern Africa, located in Mozambique, has recently partnered with British-based Bolina Booms to provide log screen booms to maintain the hydropower plant. The plant, operated by Hidroélectrica de Cahora Bassa, provides the majority of the energy to Mozambique’s national grid, which makes maintenance absolutely essential in order to prevent disruptions to national energy supplies. Water impounded behind the 170m high Cahora Bassa Dam
stretches 280km upstream and is subject to severe fluctuations in levels due to rainfall and other weather conditions. As a result, the plant had been experiencing ongoing operational
problems with waterborne debris overwhelming the existing boom which had been in place for a number of years and could not hold the debris back. Debris booms are able to prevent materials such as plastic,
invasive plant life or wood (such as logs or branches) from accumulating and blocking the dam, as well as preventing damage to the dam itself. Damage to the dam can occur as a result of heavy floating objects being carried at speed on the surface of the lake impacting the dam’s structure and consequently weakening it. Furthermore, obstructions to the dam’s sluice gate due to debris accumulation will reduce its capacity to channel water, in turn reducing the dam’s efficiency, which will eventually necessitate cleaning and removal of the obstruction and cause disruption to the dam’s supply and operation - further increasing maintenance costs. To overcome these issues and increase reliability of the installation, Bolina utilised its LSB600 Log Screen Boom, developed from its Traffic Control Booms tested to over 60-tonnes. It incorporates a subsurface mesh joined together to provide a seamless barrier for logs and debris, with full articulation provided between units.
Cahora Bassa in Mozambique is Africa’s fourth largest artificial lake
The unique tubular backbone of this boom system and the Bolina lug connections make the boom immensely strong without stressing the floats, which are fully demountable with the booms designed for continuous motion and heavy loads. A total of 380m of boom were shipped from the UK in containers
to Cahora Bassa, together with a gate assembly designed by the Bolina team. The gate was included to allow the passage of maintenance boats either side of the boom and is the largest that Bolina has constructed to date. The work was supervised by Bolina field engineers but undertaken by local workers employed by the power company using readily available hand tools. Construction of the boom on site was completed and then simply floated into place and secured in position, utilising the end connections from the previous boom. The new boom captures and diverts much more debris than the
previous solution and has increased operational efficiency of the plant and reduced the need for the maintenance team to clear debris from around the intakes.
12 | March 2022 |
www.waterpowermagazine.com
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